U.S. patent application number 14/409585 was filed with the patent office on 2015-07-16 for electromagnetic actuator, particularly for needle selection devices in machines for knitting, hosiery or the like, with high gauge.
This patent application is currently assigned to SANTONI S.P.A.. The applicant listed for this patent is SANTONI S.P.A.. Invention is credited to Ettore Lonati, Fausto Lonati, Tiberio Lonati.
Application Number | 20150197880 14/409585 |
Document ID | / |
Family ID | 46832901 |
Filed Date | 2015-07-16 |
United States Patent
Application |
20150197880 |
Kind Code |
A1 |
Lonati; Ettore ; et
al. |
July 16, 2015 |
ELECTROMAGNETIC ACTUATOR, PARTICULARLY FOR NEEDLE SELECTION DEVICES
IN MACHINES FOR KNITTING, HOSIERY OR THE LIKE, WITH HIGH GAUGE
Abstract
An electromagnetic actuator, particularly for needle selection
devices in machines for knitting, hosiery or the like, with high
gauge. The electromagnetic actuator comprises a main magnet which
has at least two polar regions which are side-by-side and separated
by a gap and two selection electromagnets, each provided with at
least one polar region which is aligned with the gap and spaced
laterally from said gap. The at least one polar region of a
selection electromagnet is arranged laterally on the side opposite
to the at least one polar region of the other selection
electromagnet with respect to the gap. The selection electromagnets
can be activated individually to generate or cancel or reduce an
attractive magnetic force at the corresponding polar region.
Inventors: |
Lonati; Ettore; (Botticino,
IT) ; Lonati; Fausto; (Brescia, IT) ; Lonati;
Tiberio; (Brescia, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SANTONI S.P.A. |
Brescia |
|
IT |
|
|
Assignee: |
SANTONI S.P.A.
Brescia
IT
|
Family ID: |
46832901 |
Appl. No.: |
14/409585 |
Filed: |
June 12, 2013 |
PCT Filed: |
June 12, 2013 |
PCT NO: |
PCT/EP2013/062113 |
371 Date: |
December 19, 2014 |
Current U.S.
Class: |
66/219 |
Current CPC
Class: |
D04B 15/78 20130101 |
International
Class: |
D04B 15/78 20060101
D04B015/78 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2012 |
IT |
MI2012A001091 |
Claims
1-15. (canceled)
16. An electromagnetic actuator, particularly for needle selection
devices in machines for knitting, hosiery or the like, with high
gauge, comprising a main magnet which has at least two polar
regions which are side-by-side and separated by a gap, further
comprising two selection electromagnets, each one provided with at
least one polar region which is aligned with said gap and spaced
laterally from said gap, the at least one polar region of a
selection electromagnet of said two selection electromagnets being
arranged laterally on the side opposite to the at least one polar
region of the other selection electromagnet of said two selection
electromagnets with respect to said gap, said selection
electromagnets being able to be activated individually to generate
or cancel or reduce an attractive magnetic force at the
corresponding polar region.
17. The electromagnetic actuator according to claim 16, wherein
said selection electromagnets are spaced laterally, on mutually
opposite sides, from said main magnet.
18. The electromagnetic actuator according to claim 16, wherein
each one of said selection electromagnets comprises a core made of
ferromagnetic material which defines, with one of its ends, the at
least one polar region of the selection electromagnet and at least
one control coil which can be supplied with electric power in order
to generate, at said at least one polar region of the selection
electromagnet, said attractive magnetic force.
19. The electromagnetic actuator according to claim 16, wherein
each one of said selection electromagnets comprises a permanent
magnet, which is connected magnetically to the corresponding at
least one polar region in order to generate, at said at least one
polar region of the selection electromagnet, said attractive
magnetic force, and at least one control coil which can be supplied
with electric power so as to cancel or reduce said attractive
magnetic force at said at least one polar region of the selection
electromagnet.
20. The electromagnetic actuator according to claim 16, wherein
said main magnet comprises a permanent magnet, which is enclosed in
a sandwich-like arrangement between two yokes, which define, with
ends thereof, two pairs of polar regions, which are separated by
said gap.
21. The electromagnetic actuator according to claim 20, wherein
each one of said two yokes of the main magnet is substantially
U-shaped with said gap formed between the two free ends of the
U-shape.
22. The electromagnetic actuator according to claim 21, wherein
said permanent magnet of the main magnet is interposed between said
two yokes proximate to the connecting region of the two arms of the
U-shape of the two yokes.
23. The electromagnetic actuator according to claim 19, wherein
said permanent magnet or said core of each selection electromagnet
is enclosed in a sandwich-like fashion between two bars, which
define, with ends thereof, two polar regions in alignment with each
other and with said gap.
24. The electromagnetic actuator according to claim 23, wherein
said two polar regions of each selection electromagnet are aligned
along a direction which is perpendicular to a direction of
side-by-side arrangement of the at least two polar regions of said
main magnet.
25. The electromagnetic actuator according to claim 24, wherein the
polar regions of said selection electromagnets are mutually aligned
along a direction which is perpendicular to said direction of
side-by-side arrangement.
26. The electromagnetic actuator according to claim 23, wherein in
each selection electromagnet a corresponding control coil is
arranged around one of the two bars which define said two polar
regions of the corresponding selection electromagnet.
27. A needle selection device for machines for knitting, hosiery or
the like, comprising an electromagnetic actuator according to claim
16, with said at least two polar regions of the main magnet
arranged in sequence along an actuation direction, and selection
elements which can be attracted magnetically and can move along
said actuation direction with respect to said electromagnetic
actuator in order to face in sequence a first polar region of said
polar regions of the main magnet, then said gap and said at least
one polar region of a selection electromagnet or said at least one
polar region of the other selection electromagnet and then a second
polar region of said at least two polar regions of the main magnet;
said selection elements comprising first selection elements which
are adapted to interact with said polar regions of said main magnet
and with said at least one polar region of a selection
electromagnet, and second selection elements adapted to interact
with said polar regions of said main magnet and with said at least
one polar region of the other selection electromagnet; said
selection elements being movable from a first position, in which
they are kept adjacent to said polar regions of the main magnet y
the magnetic attraction applied by said polar regions of the main
magnet, to a second position, in which they are spaced further from
said polar regions of said main magnet than in said first position;
the control coil of each one of said selection electromagnets being
able to be supplied with electric power in order to keep the
selection element interacting with the at least one polar region of
the corresponding selection electromagnet in said first position or
to allow the passage of the selection element which interacts with
the at least one polar region of the corresponding selection
electromagnet from said first position to said second position upon
its passage at said gap and at said at least one polar region of
the corresponding selection electromagnet.
28. The device according to claim 27, wherein said first selection
elements and said second selection elements are alternated along
said actuation direction.
29. The device according to claim 27, wherein each one of said
selection elements can move, in order to pass from said first
position to said second position, on a plane which is substantially
perpendicular to said actuation direction, through the action of
elastic means.
30. The device according to claim 27, wherein faces of said polar
regions of the main magnet and of the selection electromagnets
directed toward said selection elements are substantially coplanar.
Description
[0001] The present invention relates to an electromagnetic
actuator, particularly for needle selection devices in machines for
knitting, hosiery or the like, with high gauge.
[0002] Electromagnetic actuators for needle selection devices in
machines for knitting, hosiery or the like are known.
[0003] These electromagnetic actuators are generally composed
substantially of a main magnet, which has two side-by-side polar
regions separated by a gap, and a selection electromagnet, which is
provided with a ferromagnetic core that has at least one polar
region arranged at the gap between the two polar regions of the
main magnet. The selection electromagnet is provided with a coil
that can be supplied with electric power in order to cancel or is
reduce substantially the attractive magnetic force of the polar
region of the core of the selection electromagnet induced by the
main magnet.
[0004] Needle selection devices that use these electromagnetic
actuators generally comprise a plurality of selection elements that
are made of a material that is susceptible of magnetic attraction,
can move with respect to the electromagnetic actuator along an
activation direction and, in their motion, face the polar regions
of the main magnet and of the core of the selection
electromagnet.
[0005] The electromagnetic actuator is arranged on the machine so
that the polar regions are arranged sequentially along the
direction of activation of the selection elements so that they, in
their motion along the activation direction, face in succession
with one of their sides first one of the polar regions of the main
magnet, then the gap and the polar region of the core of the
selection electromagnet and finally the other polar region of the
main magnet.
[0006] Moreover, the selection elements can move from a first
position, in which they are adjacent or even in contact with the
above-cited polar regions, to a second position, in which they are
spaced from the polar regions with respect to the first position.
This mobility of the selection elements in the two positions
corresponds to two different activations of the elements of the
machine, generally needles, that must be selected by means of the
selection device.
[0007] In practice, in many cases the movement of the selection
elements from the second position to the first position is
contrasted by an elastic element that tends to keep the
corresponding selection element in the second position. Upstream of
the electromagnetic actuator, an abutment, constituted generally by
a cam, operates on the selection elements so that they all pass
into the first position just before or at the first polar region of
the main magnet that retains the selection elements in this
position until the gap begins. At the gap, if the coil is supplied
with electric power, the attractive force of the selection
electromagnet core, produced by the main magnet, is canceled or
substantially reduced to such an extent that it is insufficient to
contrast the force of the elastic element that makes the selection
element pass into the second position, in which it remains even
during the passage at the second polar region of the main magnet,
the attractive force of which is in itself insufficient to cause
the passage of the selection element from the second position to
the first position. Vice versa, if the coil of the selection
electromagnet is not powered, the selection electromagnet core
retains in the first position the selection element, which remains
in this position and is retained in said first position also during
the passage at the second polar region of the main magnet.
[0008] The selection element, depending on whether it is in the
first position or in the second position, with consequent
engagement or lack thereof with other elements of the machine,
causes a different actuation of the element, generally a needle, of
the machine that is correlated therewith, obtaining the desired
selection.
[0009] In electromagnetic actuators of this kind, difficulties in
sizing and supplying power to the selection electromagnet coil are
observed, since in order to obtain a precise effect on the
selection elements the intensity of the magnetic field induced by
the electric power supply of the coil must be, at the gap, i.e. at
the polar region of the selection electromagnetic coil, essentially
equal and opposite to that of the magnetic field that is induced
permanently in the selection electromagnet core by the main magnet.
If the intensity of the magnetic field induced by the power supply
of the coil were significantly lower or higher than that of the
permanent magnetic field induced in the selection electromagnet
core, the polar region of the selection electromagnet core would
still produce an attraction of the selection element, achieving an
effect that is the opposite to the desired one.
[0010] The sizing and power supply of the selection electromagnet
coil in electromagnetic actuators of the known type are
complicated, since the intensity of the magnetic field induced at
the polar region of the selection electromagnet, and therefore the
attraction force exerted by this polar region on the selection
element, vary as a function of the number of selection elements
that are in contact with or adjacent to the polar regions of the
main magnet, since the selection elements produce, through their
presence, a variation of the magnetic field of the main magnet,
which in turn causes variations of the magnetic field induced in
the selection electromagnet core that is arranged inside the main
magnet, at the gap, between its polar regions.
[0011] In electromagnetic actuators of the known type, in order to
avoid selection errors, it would be necessary to supply the
selection electromagnet coil with a current the intensity of which
is variable as a function of the various selection conditions, with
considerable burdens as regards the management of the actuation of
the electromagnetic actuators.
[0012] Italian patent no. 1,357,140 in the name of the same
Applicant describes an electromagnetic actuator that solves the
problems described above due to the fact that the selection
electromagnet has at least one polar region that is aligned with
the gap of the two polar regions of the main magnet and is spaced
laterally from said gap.
[0013] Problems have been observed in the use of this type of
electromagnetic actuator to actuate needle selection devices in
circular hosiery or knitting machines with high gauge.
[0014] The dimension of the polar region of the selection
electromagnet in alignment with the gap of the main magnet, along
the direction of actuation of the selection elements with respect
to the electromagnetic actuator, in fact must not be too wide; in
particular, it must be smaller than or equal to the distance
between two contiguous selection elements, because otherwise the
selection electromagnet, by means of its polar region, would act
simultaneously on two contiguous selection elements and therefore
would be unable to actuate two contiguous selection elements
differently.
[0015] This requirement clashes with the need for the same
dimension of the polar region of the selection electromagnet to be
wide enough to give time to the selection element on which it acts
to move away enough to avoid being attracted again by the polar
region of the main magnet that follows the polar region of the
selection electromagnet when one wishes to actuate the selection
element so that it passes from the first position to the second
position.
[0016] In the case of machines with high gauges, i.e., with a very
small distance between the selection elements along their actuation
direction with respect to the electromagnetic actuator, and with
high actuation speeds of the selection elements with respect to the
selection electromagnet, even by utilizing all the space available,
a dimension of the polar expansion of the selection electromagnet
that is smaller than this distance is too small to be able to
actuate correctly the selection elements.
[0017] The aim of the present invention is to solve the problem
described above, providing an electromagnetic actuator for needle
selection devices in machines for knitting, hosiery or the like
that allows correct actuation of the selection elements even in
case of high gauges and with high actuation speeds of the selection
elements with respect to the electromagnetic actuator.
[0018] Within this aim, an object of the present invention is to
provide an electromagnetic actuator that is highly reliable in
operation.
[0019] Another object of the invention is to provide an
electromagnetic actuator that has a limited space occupation.
[0020] A further object of the invention is to provide an
electromagnetic actuator that retains the advantages of the
electromagnetic actuator according to Italian patent no. 1,357,140
in terms of manufacturing and actuation simplicity.
[0021] This aim, as well as these and other objects that will
become more apparent hereinafter, are achieved by an
electromagnetic actuator, particularly for needle selection devices
in machines for knitting, hosiery or the like, with high gauge,
comprising a main magnet which has at least two polar regions which
are side-by-side and separated by a gap, characterized in that it
comprises two selection electromagnets, each one provided with at
least one polar region which is aligned with said gap and spaced
laterally from said gap, the at least one polar region of a
selection electromagnet of said two selection electromagnets being
arranged laterally on the side opposite to the at least one polar
region of the other selection electromagnet of said two selection
electromagnets with respect to said gap, said selection
electromagnets being able to be activated individually to generate
or cancel or reduce an attractive magnetic force at the
corresponding polar region.
[0022] Further characteristics and advantages of the invention will
become more apparent from the description of a preferred but not
exclusive embodiment of the electromagnetic actuator according to
the invention, illustrated by way of non-limiting example in the
accompanying drawings, wherein:
[0023] FIG. 1 is a perspective view of the actuator according to
the invention which faces a plurality of selection elements of a
needle selection device of a circular knitting machine, which are
shown only partially for the sake of simplicity;
[0024] FIG. 2 is a view, similar to FIG. 1, of the actuator
according to the invention, showing a selection element;
[0025] FIG. 3 is a view, similar to FIG. 1, of the actuator
according to the invention, showing another selection element;
[0026] FIG. 4 is a lateral elevation view of the electromagnetic
actuator according to the invention, applied to a needle selection
device of the dial of a circular knitting machine, showing a
selection element in a first position;
[0027] FIG. 5 is a lateral elevation view of the electromagnetic
actuator according to the invention, applied to a needle selection
device of the dial of a circular knitting machine, showing the
selection element of FIG. 4 in a second position;
[0028] FIG. 6 is a lateral elevation view of the electromagnetic
actuator according to the invention, applied to a needle selection
device of the dial of a circular knitting machine, showing another
selection element in a first position;
[0029] FIG. 7 is a lateral elevation view of the electromagnetic
actuator according to the invention, applied to a needle selection
device of the dial of a circular knitting machine, showing the
selection element of FIG. 6 in a second position;
[0030] FIG. 8 is a schematic sectional view of FIG. 4 along the
plane VIII-VIII, showing a plurality of selection elements;
[0031] FIGS. 9 to 11 are schematic views of an actuation sequence
of a selection element with the electromagnetic actuator according
to the invention shown in a front elevation view;
[0032] FIGS. 12 to 14 are schematic views of another actuation
sequence of a selection element with the electromagnetic actuator
according to the invention in a front elevation view.
[0033] With reference to the cited figures, the electromagnetic
actuator according to the invention, generally designated by the
reference numeral 1, comprises a main magnet 2, which has at least
two polar regions 3a, 4a, 3b, 4b that are arranged side by side and
separated by a gap 5a, 5b.
[0034] According to the invention, the electromagnetic actuator
also comprises two selection electromagnets 6, 7, each one provided
with at least one polar region 6a, 6b, 7a, 7b that is aligned with
the gap 5a, 5b of the main magnet 2 and is spaced laterally from
said gap 5a, 5b. The at least one polar region 6a, 6b of the
selection electromagnet 6 is arranged laterally on the side
opposite to the at least one polar region 7a, 7b of the other
selection electromagnet 7 with respect to the gap 5a, 5b of the
main magnet 2. The selection electromagnets 6, 7 can be actuated
individually in order to generate or cancel or reduce an attractive
magnetic force at the corresponding polar region 6a, 6b, 7a, 7b, as
will become more apparent hereinafter.
[0035] Conveniently, the selection electromagnets 6, 7 are spaced
laterally from the main magnet 2 so that the gap 5a, 5b of the main
magnet 2 is completely free from the polar regions of selection
electromagnets.
[0036] More particularly, the main magnet 2, in the illustrated
embodiment, comprises a permanent magnet 8, which is enclosed in a
sandwich-like fashion between two yokes 9a, 9b, which form, with
their ends, two pairs of polar regions, respectively a first pair
of polar regions 3a, 3b and a second pair of polar regions 4a, 4b,
in which the polar regions 3a, 4a are formed by the yoke 9a and the
polar regions 3b, 4b are formed by the yoke 9b. The polar regions
3a, 4a of the yoke 9a are separated by a corresponding gap 5a, and
likewise the polar regions 3b, 4b of the yoke 9b are separated by a
corresponding gap 5b.
[0037] Each one of the two yokes 9a, 9b of the main magnet 2 is
substantially U-shaped, with the corresponding gap 5a, 5b formed
between the two free ends of the U-shape.
[0038] The permanent magnet 8 of the main magnet 2 is interposed
between the two yokes 9a, 9b proximate to the region at which the
two arms of each U-shape of the two yokes 9a, 9b join.
[0039] According to a constructive variation, which is not shown,
the main magnet 2 can be provided with a single yoke and therefore
with a single gap instead of two mutually aligned gaps as
shown.
[0040] Each selection electromagnet 6, 7, in the illustrated
embodiment, comprises a permanent magnet 10, 11, which is enclosed
in a sandwich-like fashion between two mutually parallel bars 12a,
12b, 13a, 13b, which form, with one of their ends, two polar
regions 6a, 6b, 7a, 7b, which are aligned with each other and with
the gaps 5a, 5b of the main magnet 2. The two bars 12a, 12b, 13a,
13b are made of ferromagnetic material, so that by the effect of
the permanent magnet 10, 11, an attractive force is generated, at
the polar regions 6a, 6b, 7a, 7b, on a body made of ferromagnetic
material that faces said polar regions 6a, 6b, 7a, 7b. Each
selection electromagnet 6, 7 comprises an actuation coil 14, 15,
which can be supplied with electric power for cancellation or
reduction of the attractive magnetic force at the polar regions 6a,
6b, 7a, 7b.
[0041] The two polar regions 6a, 6b, 7a, 7b of each selection
electromagnet 6, 7 are arranged side-by-side along a direction 16
that is substantially perpendicular to the direction of
side-by-side arrangement 17 of the two polar regions 3a, 4a and 3b,
4b of the pairs of polar regions of the main magnet 2.
[0042] Conveniently, the polar regions 6a, 6b, 7a, 7b of the
selection electromagnets 6, 7 are all mutually aligned along a
direction 16 that is perpendicular to the direction of side-by-side
arrangement 17 of the two polar regions 3a, 4a and 3b, 4b of the
pairs of polar regions of the main magnet 2 between which the gaps
5a, 5b, also aligned along the direction 16, are formed.
[0043] Preferably, in each selection electromagnet 6, 7 the
corresponding control coil 14, 15 is arranged around one of the two
bars 12a, 12b, 13a, 13b that form the two polar regions 6a, 6b, 7a,
7b of the corresponding selection electromagnet 6, 7. In the
illustrated embodiment, the control coil 14 of the selection
electromagnet 6 is arranged around the bar 12a, while the control
coil 15 of the selection electromagnet 7 is arranged around the bar
13a.
[0044] The electromagnetic actuator according to the invention is
intended to be used preferably in needle selection devices for
machines for knitting, hosiery or the like, with the two polar
regions or the two pairs of polar regions 3a, 4a, 3b, 4b of the
main magnet 2 arranged in sequence, in a substantially coplanar
position, along an actuation direction, designated by the arrow 18,
so that they face selection elements 22, 23 that are made of a
material susceptible to magnetic attraction and can move along said
actuation direction 18 with respect to the electromagnetic actuator
1.
[0045] In this manner, the selection elements 22, 23 face
sequentially a first polar region or a first pair of polar regions
3a, 3b of the main magnet 2, then the gap 5a, 5b and the two polar
regions 6a, 6b of a selection electromagnet 6 or the two polar
regions 7a, 7b of the other selection electromagnet 7 and then a
second polar region or a second pair of polar regions 4a, 4b of the
main magnet 2.
[0046] The selection elements 22, 23 comprise first selection
elements 22, which are adapted to interact with the polar regions
3a, 3b, 4a, 4b of the main magnet 2 and with the two polar regions
6a, 6b of the selection electromagnet 6, and second selection
elements 23, which are adapted to interact with the polar regions
3a, 3b, 4a, 4b of the main magnet 2 and with the two polar regions
7a, 7b of the other selection electromagnet 7. Essentially, as is
evident from the drawings, the first selection elements 22 are
shorter than the second selection elements 23, which, thanks to
their greater length, bypass the selection electromagnet 6 intended
to interact with the first selection elements 22 and face the other
selection electromagnet 7 intended to interact with them.
[0047] The selection elements 22, 23 are arranged so that in each
instance, as a consequence of movement imparted to the selection
elements 22, 23 with respect to the electromagnetic actuator 1
according to the invention, the gap 5a, 5b of the main magnet 2
faces a first selection element 22 and then a second selection
element 23. In practice, the selection elements 22, 23 are arranged
so that the first selection elements 22, which are shorter, are
alternated with the second selection elements 23, which are
longer.
[0048] The selection elements 22, 23 can move from a first
position, in which they are kept adjacent to the polar regions 3a,
3b, 6a, 6b, 7a, 7b, 4a, 4b by the magnetic attraction exerted by
said polar regions, to a second position, in which they are further
spaced from the polar regions 3a, 3b, 6a, 6b, 7a, 7b, 4a, 4b than
in the first position. Each selection element 22, 23, in order to
pass from the first position to the second position and vice versa,
can move on a plane that is perpendicular to the actuation
direction 18 and the movement from the second position to the first
position is contrasted by elastic means that can be constituted by
a spring 24.
[0049] Without altering the fact that the electromagnetic actuator
according to the invention can be used also with other types of
needle selection devices, merely by way of example and only to
further clarify its actuation, the operation of the electromagnetic
actuator according to the invention is explained hereinafter with
reference to a needle selection device 30 of the dial 31 of a
circular knitting machine, similar to the one shown in Italian
patent no. 1,293,789 in the name of the same Applicant, which uses,
as selection elements 22, 23, levers which are pivoted, about a
pivoting axis 32, to the end of the corresponding needle 30 that is
opposite to the tip and can oscillate about said pivoting axis 32
in order to pass from the first position to the second position and
vice versa. Specifically, the device shown in Italian patent no.
1,293,789 is provided with selection elements constituted by levers
that have the same length, whereas the selection device shown in
the accompanying drawings is provided with selection elements that
are arranged so as to form alternately a first selection element
22, constituted by a short lever, and a second selection element
23, constituted by a long lever.
[0050] With an electromagnetic actuator according to the invention,
each selection element 22, 23 is moved along the actuation
direction 18 with respect to the electromagnetic actuator 1. Before
the selection elements 22, 23 reach the first pair of polar regions
3a, 3b of the main magnet 2 or thereat, an abutment, constituted
for example by a cam, acts on them, causing their passage from the
second position to the first position, i.e., pushing them toward
said polar regions 3a, 3b, which, as a consequence of their
magnetic attraction, retain the selection elements 22, 23 in the
first position, as shown in FIGS. 9 and 12. When one of the first
selection elements 22 arrives at the gap 5a, 5b and thus faces with
one of its portions the polar regions 6a, 6b of the selection
electromagnet 6, if the actuation coil 14 is not supplied with
power, the attractive action of these polar regions 6a, 6b produced
by the permanent magnet 10 retains the first selection element 22
in the first position, as shown in FIGS. 2, 4, 10. Subsequently,
said first selection element 22 faces the second pair of polar
regions 4a, 4b of the main magnet 2 that retain said first
selection element 22 in the first position, as shown in FIG.
11.
[0051] If vice versa the control coil 14 is supplied with power,
the attractive force of the polar regions 6a, 6b of the selection
electromagnet 6 is canceled or reduced and the first selection
element 22 passes, through the action of the spring 24, to the
second position, i.e., it moves away from the polar region, as
shown in FIGS. 5 and 13. Then, during passage at the second pair of
polar regions 4a, 4b of the main magnet 2, said first selection
element 22 remains in the second position, as shown in FIG. 14.
[0052] Likewise, when one of the second selection elements 23
arrives at the gap 5a, 5b of the main magnet 2, by not powering or
powering the control coil 15 of the selection electromagnet 7 said
second selection element 23 is kept in the first position, as shown
in FIG. 6, so that subsequently, by facing the second pair of polar
regions 4a, 4b of the main magnet 2, said second selection element
23 remains in the first position, as shown in FIG. 11, or the
transition of said second selection element 23 to the second
position through the action of the spring 24 is produced, as shown
in FIGS. 7 and 13, so that subsequently, by facing the second pair
of polar regions 4a, 4b of the main magnet 2, said second selection
element 23 remains in the second position, as shown in FIG. 14.
[0053] The different position assumed by the selection element 22,
23, after the passage at the gap 5a, 5b of the polar regions 3a,
3b, 4a, 4b and of the selection electromagnets 6, 7 is used for an
engagement or disengagement of the selection element 22, 23 with
actuation elements, for example cams, so as to cause a different
actuation of the needle 30, to which the selection elements 22, 23
is connected and which is thus selected by means of the device.
[0054] The electromagnetic actuator according to the invention can
also be provided in other embodiments that are within the
protective scope of the present invention, for example by provision
of the selection electromagnets 6, 7 with a simple core of
ferromagnetic material instead of a permanent magnet. Regardless of
the fact that the cores of the selection electromagnets 6, 7 may
also have other shapes, the selection electromagnets may also be
provided substantially as described and illustrated with reference
to the accompanying drawings, simply by replacement of the
permanent magnets 10, 11 described with reference to the
above-cited drawings by ferromagnetic cores. Optionally, the cores
of the selection electromagnets 6, 7 can be provided monolithically
with the bars 12a, 12b, 13a, 13b of the corresponding selection
electromagnet 6, 7.
[0055] In these further embodiments, in which the selection
electromagnet does not have a permanent magnet, the operation of
the electromagnetic actuator differs from the one described above
in that when one wishes to keep a selection element 22, 23 in the
first position at the gap 5a, 5b of the main magnet 2 the control
coil 14, 15 of the selection electromagnet 6, 7 is supplied with
power so that an attractive force is generated at the polar regions
6a, 6b, 7a, 7b, whereas when one wishes to induce the passage of
the selection element 22, 23 from the first position to the second
position the control coil 14, 15 of the selection electromagnet 6,
7 is not supplied with power.
[0056] Conveniently, the faces of the polar regions 3a, 3b, 6a, 6b,
7a, 7b, 4a, 4b of the main magnet 2 and of the selection
electromagnets 6, 7 directed toward the selection elements 22, 23
are substantially co-planar.
[0057] Optionally, direct contact between the selection elements
22, 23 and the polar regions 3a, 3b, 6a, 6b, 7a, 7b, 4a, 4b can be
avoided by the provision of adapted resting elements 19 for the
selection elements 22, 23 for example proximate to the polar
regions 3a, 3b, 4a, 4b of the main magnet 2.
[0058] It should be noted that in the electromagnetic actuator
according to the invention, by means of the provision of two
selection electromagnets 6, 7 arranged laterally on mutually
opposite sides with respect to the gap 5a, 5b of the main magnet 2
and by the use of selection elements 22, 23 of different lengths
which are mutually alternated and face respectively one and the
other of the selection electromagnets 6, 7, in practice the space
between the selection elements 22, 23 that is available to operate
with one or the other of the selection electromagnets 6, 7 in
practice is doubled. In this manner it is possible to have polar
regions 6a, 6b, 7a, 7b of the selection electromagnets 6, 7 that
are wide enough to have a precise and reliable actuation of the
selection elements 22, 23 in high-gauge machines, i.e., having a
reduced distance between two contiguous selection elements 22, 23,
actuated at high speed, i.e., with a high movement speed of the
selection elements 22, 23 along the actuation direction 18 with
respect to the electromagnetic actuator 1.
[0059] In practice, by means of the electromagnetic actuator
according to the invention it is possible to actuate in a different
manner two contiguous selection elements 22, 23, i.e., keep one
selection element 22 or 23 in the first position while the
contiguous selection element 23 or 22 is moved to the second
position or vice versa. This fact, in the use of the
electromagnetic actuator according to the invention in a needle
selection device of a hosiery or knitting machine or the like,
means that it is possible to perform what is called
needle-by-needle selection.
[0060] Furthermore, the solution of using a single main magnet 2
with two selection electromagnets 6, 7 has the advantage of a
limited space occupation which simplifies the installation of the
electromagnetic actuator on machines.
[0061] In practice it has been found that the electromagnetic
actuator according to the invention achieves fully the intended aim
and objects, since it allows correct actuation of the selection
elements even in the case of high gauges and with high actuation
speeds of the selection elements with respect to the
electromagnetic actuator.
[0062] The electromagnetic actuator thus conceived is susceptible
of numerous modifications and variations, all of which are within
the scope of the appended claims; all the details may further be
replaced with other technically equivalent elements.
[0063] In practice, the materials used, as long as they are
compatible with the specific use, as well as the dimensions, may be
any according to the requirements and the state of the art.
[0064] The disclosures in Italian Patent Application No.
MI2012A001091 from which this application claims priority are
incorporated herein by reference.
[0065] Where technical features mentioned in any claim are followed
by reference signs, those reference signs have been included for
the sole purpose of increasing the intelligibility of the claims
and accordingly such reference signs do not have any limiting
effect on the interpretation of each element identified by way of
example by such reference signs.
* * * * *